Inhibition of carburetor icing



2,982,629 INHIBITION OF CARBURETOR ioiNo Harry J. Andress, Jr., Pitman, and Paul Y. C. Gee, Woodbury, N.J., assignors to Socony Mobil Oil Company, Inc., a corporation of New York No Drawing. Filed Jan. 7, 1958, Ser. No. 707,460

3 Claims. (CL'44-71) This invention relates to gasoline compositions adapted to improve the operation of internal combustion engines. It is more particularly concerned with motor .fuels that provide improved engine operation under cool, humid weather conditions.

As is well known to those skilled in the art, frequent stalling of automobile engines, especially during the warmup period, has been a common occurrence. This difficulty is most pronounced in postwar cars having automatic transmissions and a consequent limit on the maximum permissible idle speed. Stalling of this type, of course, is a definite safety hazard, as well as a decided inconvenience in frequent restarting of the engine.

It is now recognized that stalling during the warmup period is attributable to the formation of ice on the throttle plate and the carburetor barrel near it. The water which forms the ice does not come from the gasoline, i.e., as entrained water, but from the air that enters the carburetor. As has been mentioned hereinbefore, stalling generally occurs in cool, humid Weather, when the temperatures are above about 30 F. and below about 60 F. and the relative humidity is about 65 percent and higher, up to 100 percent. The most critical conditions are temperatures of 35-40 F. and 100 percent relative humidity.

As the gasoline evaporates in the carburetor, it reduces the temperature of the surrounding metal by as much as 50 F. Moisture in the incoming air comes in contact with these parts and begins to build up ice on the throttle plate and in the carburetor barrel. The more moist this air is, the greatenthe buildup of ice. Then, when the engine is id-led, the throttle plate closes and the ice chokesotl the normal small flow of air through the small clearance between the throttle plate and the carburetor wall. This causes the engine to stall. The engine can usually be restarted when theheat from the exhaust manifold melts the ice sufficiently. However, stalling will continue until the engine is completely warmed up.

Gasoline is a mixture of hydrocarbonshaving an initial boiling point falling between about 75 F. and about 135 F. and an end-boiling point falling between about 250 F. and about 450 F. The boiling range of the gasoline,-oi course, reflects on its volatility. Thus, a higher boiling gasoline will be less volatile and give less stalling difficulty. 'In modern engine operation, however, control of stalling by means of increased volatility is not feasible, because other performance characteristios are afiected.

It has now been found that stalling during engine warmup can be overcome simply and economically. It has been discovered that small amounts of certain succinamic acids, when added to motor gasoline, will overcome stalling difficulties attributable to carburetor icing.

Accordingly, it is an object of this'invention .to provide an improved motor fuel. Another object is to provide a motor fuel adapted to prevent stalling during engine warmup in cool, humid weather. A specific object ishto provide an antistall gasoline containing certain succinamic United States Patent Ice acids. Other objects and advantages of htis invention will become apparent to those skilled in the art, from the following detailed description. 7

, In general, this invention provides a motor gasoline containing a small amount, sufiicient to inhibit stalling,

wherein R is an alkyl group containing between about 10 and about 30 carbon atoms per alkyl group and having a tertiary carbon atom directly attached to the nitrogen atom. The amic acids can be made by any method known in the art for preparing such compounds. Preferably, they are produced by warming succinic acid anhydride with a tertiaryalkyl primary monoamine having between about 12 and about 24 carbon atoms per molecule. This can be done readily by heating a mixture of equimolar amounts of the acid anhydride and the tertiarylalkyl primary amine at a temperature of 65- C. for a period of time varying between one and th-reehours. The addition occurs readily without the formation of water. Less desirably, the amic acids can be prepared by the controlled reaction between equimolar amounts of succinic acid and the amine, with the eliminationof one mole of water per mole of amic acid produced. Care must be exercised, however, to avoid the elimination of two moles of water to form the-cyclic imide.

The amines utilizable in forming the amic acids are the tertiaryalkyl primary monoamines in which a primary amino group (NH is directly attached to a tertiary carbon atom, and which contains between about 10 and about 30 carbon atoms per tertiaryalkyl group.

Non-limiting examples of the amines are t-dodecyl primaryamine, t-tetradecyl primary amine, t-pentadecyl primary amine, t-hexadecyl primary amine, t-octadecyl primary amine, t-eicosyl primary amine, t-tetracosyl primary amine, and t-triacontyl primary amine. These amines can be prepared by several methods well known to those skilled in the art. Specific methods for preparing the t-alkyl primary amines are disclosed in the Journal of Organic Chemistry, vol. 20, page 295 et seq. (1955). Mixtures of such amines are contemplated. These can be made from a polyolefin fraction (e.g., polypropylene and polybutylene cuts) by first hydrating with sulfuric acid and water to the corresponding alcohol, converting the alcohol to alkyl chloride with dry hydrogen chloride, and finally condensing the chloride with V ammonia, under pressure, to produce a t-alkyl'primary amine mixture.

The succinamic acids contemplated herein are effective to impart antistall properties to motor gasolines. The

assented May 2, 1961- 0.50 percent, by weight of the gasoline. In preferred practice, amounts varying between about 0.01 percent and about 0.05 percent, by weight, are used.

The antistall additives of the invention may be used in the gasoline along with other antistall addition agents or other additives designed to impart other improved properties thereto. Thus, anti-knock agents, pre-ignition inhibitors, anti-rust agents, metal-deactivators, dyes, antioxidants, detergents, etc., may be present in the gasoline. Also, the gasoline may contain a small amount, from about 0.01 percent to about 1 percent, by weight, of a solvent oil or upperlube. Suitable oils, for example, include Coastal and Mid-Continent distillate oils having viscosities within the range of from about 50 to about 500 S.U.S. at 100 F. Synthetic oils, such as diester oils, polyalkylene glycols, silicones, phosphate esters, polypropylenes, polybutylenes and the like, may also be used.

The following examples are for the purpose of illustrating the additives of this invention and demonstrating the effectiveness thereof. This invention is not to be limited to the specific compositions set forth in the examples or to the operations and manipulations involved. Other materials and formulations as described hereinbefore can be used, as those skilled in the art will readily understand.

The amine reactants used in the examples are mixtures of pure amines. Amine A is a mixture of primary amines having a tertiary carbon atom of a tertiary butyl group attached to the amino (-NH group and containing 12 to 15 carbon atoms per molecule and averaging 12 carbon atoms per molecule. This mixture contains, by Weight, about 85 percent t-dodecyl primary amine, about percent t-pentadecyl primary amine, and relatively small amounts, i.e., less than 5 percent amines having less than 12 or more than 15 carbon atoms. Amine B is a mixture of tertiary alkyl primary amines containing 18 to 24 carbon atoms per molecule and averaging about carbon atoms per molecule. It has a tertiary carbon attached to the -NH group. It contains, by weight, about 40 percent t-octadecyl primary amine, about percent t-eicosyl primary amine, about 15 percent tdocosyl primary amine, about 10 percent t-tetracosyl amine, and a small amount, less than 5 percent, other amines.

EXAMPLE 1 A mixture of 100 grams (0.5 mole) of amine A, 50 grams (0.5 mole) of succinic acid anhydride, and 50 grams of xylene, as diluent, was heated with agitation to 80-85 C. for 3 hours to form the succinamic acid. The reaction product was clear and fluid at room temperature.

EXAMPLE 2 A mixture of 152 grams (0.5 mole) of amine B and 50 grams (0.5 mole) of succinic acid anhydride was stirred for 2 hours at 110 C. to form the amine B succinamic acid.

Antzstalling effectiveness The ability of the succinamic acids of this invention to inhibit engine stalling is demonstrated in the following test: a

A standard Chevrolet engine, equipped with a Holley single downdraft carburetor, was mounted in a cold room refrigerated to 50 F. A Holley carburetor was used. A thermocouple was attached to the throttle plate shaft to record the plate temperature. A /Z-lHCh insulating gasket was placed between the carburetor and manifold to prevent heat conduction. An asbestos sheet covered the entire manifold system to shield the carburetor from convection and radiation. A spray chamber was used to saturate the incoming air with moisture before entering an ice tower which cooled the air to about F.

In conducting a test, the engine was first run for about 10 minutes at 2000 r.p.m. to bring the engine temperature to equilibrium. The engine was then shutoff. When the throttle shaft temperature rose to 40 F., the engine was restarted with the idle speed set at 400 to 500 r.p.m. so that the base fuel stalled at idle in 10 seconds or less after a run-time of 20 to 40 seconds. Run-time means the time that the engine was run at 2000 r.p.m. before returning to idle.

All runs were started when the throttle shaft reached 40 F. At the instant of starting, the throttle arm was moved to the 2000 r.p.m. position and a stop watch started. At the end of the selected run-time, the throttle arm was moved to the idle position. The time required to stall was recorded. Several tests were made at each runtime and averaged.

In evaluating an additive, the base fuel was first tested followed by several concentrations of the additive. The system was flushed between tests with the fuel to be run next. Any improvement caused by the additive was reflected in a longer run-time (as compared to the base fuel) to cause stalling in 10 seconds or less when the engine was idled. The more effective the additive, the longer the run-time.

Two test gasolines were used. Gasoline X was made up, by volume, of 63 percent catalytically cracked gasoline, 17 percent straight run gasoline, 8 percent benzene, and 12 percent toluene. It had an ASTM boiling range of 104 F. to 390 F., with a 50 percent distillation (mid-boiling) point of 203 F. Gasoline Y comprised, by volume, 66 percent catalytically cracked gasoline, 2 percent straight run gasoline, 12 percent benzene, 8 percent toluene, and 12 percent butanes. It had an ASTM distillation range of F. to 296 F. and a mid-boiling point of 200 F.

The results of a series of stalling tests on these gasolines and on the gasolines containing varying amounts of the compound of Example 1 are set forth in the following table.

TABLE Run Tim Test No. Compound Gasoline Conen, to 10 Sec Added Wt. Per- Stall Time cent (See) None X 0.0 Example 1.. X 0.01 --do X 0.02 130 None Y 0.0 60 Example 1. Y 0.013 -do Y 0.005

From the data in the foregoing table it will be noted that the succinamic acids contemplated herein are effective to prevent icing and stalling. Although not exactly equivalent in effectiveness, other additives as defined herein are also useful to prevent stalling.

Although the present invention has been described with preferred embodiments, it is to be understood that modifications and variations may be resorted to, without departing from the spirit and scope of this invention, as those skilled in the art will readily understand. Such variations and modifications are considered to be within the purview and scope of the appended claims.

What is claimed is:

1. A motor gasoline containing a small amount, sufficient to prevent stalling, of a compound having the formula;

0H RHNC-OH:-CHz-O wherein R is a tertiary alkyl group containing between about 10 carbon atoms and about 30 carbon atoms and having a tertiary carbon atom directly attached to the nitrogen atom.

wherein R is a mixture of tertiary alkyl group having a tertiary carbon atom directly attached to the nitrogen atom and comprising about 85 weight percent d odecyl, l

and about 10 weight percent pentadecyl.

References Cited in the file of this patent UNITED STATES PATENTS Balle Feb. 27, Dietrich Apr. 14, Rocchini Mar. 11, Rocchini July 22-, Smith et al. Jan. 11, Duncan et al. Apr. 19, Rocchini Sept. 20, Gaston et a1. July 15, Cantrell et a1. Dec. 2, Vitalis et a1. May 12, Mills Sept. 29,

OTHER REFERENCES 1942 I a 1952 r Petroleum Refining With Chemicals, Kalichevskyand 20 Kobe, Elsevier Pub. Co., 1956, page 480.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION 1 Patent No 2,982,629 May 2, 1961 Harry J. Andress, Jr. V et al.

Y 7 It is hereby certified that error appears in -the ab ove numbered patentrequiring correction and that the said Letters Paten t should read as "corrected below.

Column 2, lines 7 to l0 the formula s hould appear as shown below instead of as in the patent: 5

OH RHN-C-CH -CH -C 0 I Signed and sealed this 13th day of February 1962. (SEAL) Attest:

ERNEST w. SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents 

1. A MOTOR GASOLINE CONTAINING A SMALL AMOUNT, SUFFIFICIENT TO PREVENT STALLING, OF A COMPOUND HAVING THE FORMULA, 